Liquid crystal device and manufacturing method of the same

ABSTRACT

A liquid crystal display and a manufacturing method are provided. A liquid crystal display according to an exemplary embodiment of the present invention includes a first substrate, a second substrate facing the first substrate, a field generating electrode disposed on at least one of the first substrate and the second substrate, an alignment layer disposed on the field generating electrode, and a liquid crystal layer interposed between the first substrate and the second substrate, including liquid crystal molecules and a second alignment polymer, wherein the first alignment polymer is formed by light-irradiating the alignment agent and the first alignment aids and the second alignment polymer is formed by light-irradiating the liquid crystal molecules and the second alignment aids, and the first alignment aids and the second alignment aids include a mesogen and a photo-polymerizable group coupled to the mesogen.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from and the benefit of Korean PatentApplication No. 10-2009-0079468, filed on Aug. 26, 2009, which is herebyincorporated by reference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Exemplary embodiments of the present invention relate to a liquidcrystal display and a manufacturing method thereof.

2. Discussion of the Background

Liquid crystal displays are widely used as flat panel displays. A liquidcrystal display may include two display panels on which field generatingelectrodes are formed, and a liquid crystal layer interposed between thepanels. In the liquid crystal display, voltages may be applied to thefield generating electrodes so as to generate an electric field over theliquid crystal layer, such that the alignment of liquid crystalmolecules of the liquid crystal layer may be determined by the electricfield. Accordingly, the polarization of incident light is controlled,thereby resulting in image display.

A liquid crystal display may use a liquid crystal material that issuitable to control the transmittance of light and result in the displayof desired images. Particularly, according to the various uses of theliquid crystal display, characteristics such as low voltage driving, ahigh voltage holding ratio (VHR), a wide viewing angle characteristic, awide range of operation temperature, and high speed response arebeneficial.

The liquid crystal layer may include a liquid crystal composition thatis mixed with the liquid crystal molecules of various kinds to achievevarious beneficial characteristics.

Further, initial alignment of the liquid crystal molecules is important.

To obtain good initial alignment of the liquid crystal molecules,pre-tilt thereof is often uniformly controlled. When the pre-tilt of theliquid crystal molecules is non-uniform, the initial alignment of theliquid crystal molecules may be scattered such that it is difficult tocontrol the light passing through the liquid crystal layer. In thiscase, the contrast ratio may be decreased, and the difference of thepre-tilt may be shown as an afterimage such that the displaycharacteristics may be deteriorated.

SUMMARY OF THE INVENTION

Exemplary embodiments of the present invention prevent the deteriorationof the voltage holding ratio generated when only one of a liquid crystallayer and an alignment layer includes a reactive mesogen.

Additional features of the invention will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention.

An exemplary embodiment of the present invention discloses a liquidcrystal display including a first substrate, a second substrate facingthe first substrate, a field generating electrode disposed on at leastone of the first substrate and the second substrate, an alignment layerdisposed on the field generating electrode, the alignment layerincluding an alignment agent and a first alignment polymer, and a liquidcrystal layer interposed between the first substrate and the secondsubstrate, the liquid crystal layer including liquid crystal moleculesand a second alignment polymer, wherein the first alignment polymer isformed by light-irradiating the alignment agent and first alignmentaids, and the second alignment polymer is formed by light-irradiatingthe liquid crystal molecules and second alignment aids and wherein thefirst alignment aids and the second alignment aids comprise a mesogenand a photo-polymerizable group coupled to the mesogen.

An exemplary embodiment of the present invention also discloses a methodfor manufacturing a liquid crystal display, including forming a fieldgenerating electrode on at least one of a first substrate and a secondsubstrate, the second substrate facing the first substrate, forming analignment layer on the field generating electrode, the alignment layerincluding an alignment agent and first alignment aids, assembling thefirst substrate and the second substrate, forming a liquid crystal layerbetween the first substrate and the second substrate, the liquid crystallayer including liquid crystal molecules and second alignment aids,applying a voltage between the first substrate and the second substrate,and forming a first alignment polymer and a second alignment polymer bylight-irradiating the alignment layer and the liquid crystal layer, in astate in which the voltage is applied between the first substrate andthe second substrate.

According to the present invention, the alignment layer and the liquidcrystal molecules of the liquid crystal display include the alignmentaids such that the exposure efficiency may be improved, anddeterioration of the voltage holding ratio may be prevented.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an equivalent circuit diagram of one pixel of a liquid crystaldisplay according to an exemplary embodiment of the present invention.

FIG. 2 is a layout view of a liquid crystal display according to anexemplary embodiment of the present invention, and FIG. 3 is across-sectional view taken along the line III-III′ of FIG. 2.

FIG. 4 is a top plan view showing a pixel electrode according to anexemplary embodiment of the present invention.

FIG. 5 is a top plan view of a basic electrode in a liquid crystaldisplay according to an exemplary embodiment of the present invention.

FIG. 6A and FIG. 6B are schematic diagrams showing a method for forminga pre-tilt of liquid crystal molecules through alignment aids accordingto an exemplary embodiment of the present invention.

FIG. 7 is a layout view of a liquid crystal display according to anotherexemplary embodiment of the present invention, and FIG. 8 is across-sectional view taken along the line VIII-VIII′ of FIG. 7.

FIG. 9 is a graph showing a voltage holding ratio according to existenceof alignment aids in a liquid crystal layer.

FIG. 10A, FIG. 10B, FIG. 10C, and FIG. 10D are graphs showing avariation of a voltage holding ratio according to an irradiation amountof ultraviolet (UV) rays.

FIG. 11 is a graph showing an afterimage according to existence ofalignment aids of a liquid crystal layer.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The invention is described more fully hereinafter with reference to theaccompanying drawings, in which exemplary embodiments of the inventionare shown. This invention may, however, be embodied in many differentforms and should not be construed as limited to the embodiments setforth herein. Rather, these exemplary embodiments are provided so thatthis disclosure is thorough, and will fully convey the scope of theinvention to those skilled in the art. In the drawings, the size andrelative sizes of layers and regions may be exaggerated for clarity.Like reference numerals in the drawings denote like elements.

It will be understood that when an element or layer is referred to asbeing “on” or “connected to” another element or layer, it can bedirectly on or directly connected to the other element or layer, orintervening elements or layers may be present. In contrast, when anelement is referred to as being “directly on” or “directly connected to”another element or layer, there are no intervening elements or layerspresent.

FIG. 1 is an equivalent circuit diagram of one pixel of a liquid crystaldisplay according to an exemplary embodiment of the present invention.

Referring to FIG. 1, a liquid crystal display according to an exemplaryembodiment of the present invention includes a thin film transistorarray panel 100 and a common electrode panel 200 facing each other, anda liquid crystal layer 3 interposed therebetween.

The liquid crystal display according to an exemplary embodiment of thepresent invention includes signal lines including a plurality of gatelines GL, a plurality of pairs of data lines DLa and DLb, a plurality ofstorage electrode lines SL, and a plurality of pixels PX connectedthereto.

The pixel PX includes a pair of sub-pixels PXa and PXb. The sub-pixelPXa includes a switching element Qa, a liquid crystal capacitor Clca,and a storage capacitor Csta. The sub-pixel PXb includes a switchingelement Qb, a liquid crystal capacitor Clcb, and a storage capacitorCstb.

The switching element Qa and the switching element Qb are three-terminalelements, such as, for example, a thin film transistor, provided on thethin film transistor array panel 100. The switching element Qa includesa control terminal connected to the gate line GL, an input terminalconnected to the data line DLa, and an output terminal connected to theliquid crystal capacitor Clca and the storage capacitor Csta. Theswitching element Qb includes a control terminal connected to the gateline GL, an input terminal connected to the data line DLb, and an outputterminal connected to the liquid crystal capacitor Clcb and the storagecapacitor Cstb.

The liquid crystal capacitor Clca and the liquid crystal capacitor Clcbeach uses a common electrode 270 and a sub-pixel electrode 191 a and asub-pixel electrode 191 b, respectively, as two terminals. The liquidcrystal layer 3 between the sub-pixel electrode 191 a and sub-pixelelectrode 191 b and the common electrode 270 functions as a dielectricmaterial.

The storage capacitor Csta and the storage capacitor Cstb are coupled tothe liquid crystal capacitor Clca and the liquid crystal capacitor Clcb,respectively. The storage capacitor Csta and the storage capacitor Cstbare formed between a storage electrode line SL provided on the thin filmtransistor array panel 100 and a sub-pixel electrode 191 a and asub-pixel electrode 191 b, respectively. The sub-pixel electrode 191 aand the sub-pixel electrode 191 b are overlapped with an insulatorinterposed therebetween, and a voltage such as the common voltage Vcommay be applied thereto.

The voltage charged at the liquid crystal capacitor Clca may be slightlydifferent from the voltage charged at the liquid crystal capacitor Clcb.For example, the data voltage applied to the liquid crystal capacitorClca may be established to be always lower or higher than the datavoltage applied to the corresponding liquid crystal capacitor Clcb. Whenthe voltages of the liquid crystal capacitor Clca and the liquid crystalcapacitor Clcb are properly controlled, an image viewed from the lateralside closely approximates an image viewed from the frontal side, therebyimproving the lateral visibility of the liquid crystal display.

FIG. 2 is a layout view of a liquid crystal display according to anexemplary embodiment of the present invention, and FIG. 3 is across-sectional view taken along the line III-III′ of FIG. 2. FIG. 4 isa top plan view showing a pixel electrode according to an exemplaryembodiment of the present invention. FIG. 5 is a top plan view of abasic electrode in a liquid crystal display according to an exemplaryembodiment of the present invention.

Referring to FIG. 2 and FIG. 3, a liquid crystal display according to anexemplary embodiment of the present invention includes a thin filmtransistor array panel 100 and a common electrode panel 200 facing eachother, and a liquid crystal layer 3 interposed between the thin filmtransistor array panel 100 and the common electrode panel 200.

The thin film transistor array panel 100 will be firstly described indetail.

A plurality of gate lines 121 and a plurality of storage electrode lines131 and storage electrode lines 135 are disposed on an insulationsubstrate 110.

The gate lines 121 transmit gate signals and substantially extend in thetransverse direction. Each gate line 121 includes a plurality of firstgate electrodes 124 a and second gate electrodes 124 b protruding fromthe gate line 121.

The storage electrode lines 131 may extend substantially parallel to thegate lines 121, and the plurality of storage electrode lines 135 mayextend away from the storage electrode lines 131.

However, the shapes and arrangements of the storage electrode lines 131and the storage electrode lines 135 may be modified in various forms.

A gate insulating layer 140 is disposed on the gate line 121, thestorage electrode line 131, and the storage electrode line 135, andsemiconductors 154 a and semiconductors 154 b preferably made ofamorphous or crystallized silicon are disposed on the gate insulatinglayer 140.

A pair of ohmic contacts 163 b and 165 b is disposed on the firstsemiconductor 154 b, and the ohmic contact 163 b and the ohmic contact165 b may each be formed of a silicide or of a material such as n+hydrogenated amorphous silicon in which an n-type impurity is doped witha high concentration.

A pair of data lines 171 a and 171 b and a pair of drain electrodes 175a and 175 b are disposed on the ohmic contact 163 b and the ohmiccontact 165 b, and on the gate insulating layer 140.

The data lines 171 a and the data lines 171 b, which transmit datasignals, extend substantially in the longitudinal direction, and crossthe gate lines 121 and the storage electrode lines 131. The data lines171 a and the data lines 171 b include a plurality of first sourceelectrodes 173 a and second source electrodes 173 b, respectively. Thedata lines 171 a and the data lines 171 b extend toward the first gateelectrode 124 a and the second gate electrode 124 b, respectively, andare curved with a “U” shape. The first source electrode 173 a and thefirst drain electrode 175 a are on one side of the first gate electrode124 a and the second gate electrode 124 b, respectively, and the firstdrain electrode 175 a and the second drain electrode 175 b are on theopposite side of the first gate electrode 124 a and the second gateelectrode 124 b, respectively.

The first drain electrode 175 a and the second drain electrode 175 beach include one end bordered by the first source electrode 173 a andthe second source electrode 173 b, respectively. The other end of thefirst drain electrode 175 a and the second drain electrode 175 b extendsaway from the first source electrode 173 a and the second sourceelectrode 173 b, respectively, and may have a wide area for connectionto another layer.

The shapes and arrangement of the first drain electrodes 175 a and thesecond drain electrodes 175 b and the data lines 171 a and the datalines 171 b may be modified in various forms.

The first gate electrodes 124 a, the first source electrodes 173 a, andthe first drain electrodes 175 a form the first switching element Qaalong with the first semiconductor 154 a. The second gate electrode 124b, the second source electrode 173 b, and the second drain electrode 175b form the second switching element Qb along with the secondsemiconductor 154 b. The channel of the first switching element Qa andthe second switching element Qb are respectively disposed on the firstsemiconductor 154 a, between the first source electrode 173 a and thefirst drain electrode 175 a, and the second semiconductor 154 b betweenthe second source electrode 173 b and the second drain electrode 175 b.

The ohmic contact 163 b, and the ohmic contact 165 b are interposedbetween the underlying semiconductor 154 b, and the overlying sourceelectrode 173 b, and drain electrode 175 b, and reduce contactresistance between them. Ohmic contacts are interposed similarly withreference to semiconductor 154 a. The semiconductor 154 a and thesemiconductor 154 b have a portion that is exposed without being coveredby the data line 171 a, data line 171 b, drain electrode 175 a, or drainelectrode 175 b. A portion of the semiconductor 154 a and thesemiconductor 154 b is arranged between the source electrode 173 a andthe drain electrode 175 a and the source electrode 173 b and the drainelectrode 175 b, respectively.

A lower passivation layer 180 p, preferably made of silicon nitride orsilicon oxide, is disposed on the data lines 171 a, the data lines 171b, the drain electrode 175 a, the drain electrode 175 b, and the exposedportions of the semiconductor 154 a and the semiconductor 154 b.

A color filter 230 is disposed on the lower passivation layer 180 p. Thecolor filter 230 may include three color filters, one each of red,green, and blue. A light blocking member 220 made of a single layer ordouble layers such as chromium and chromium oxide or an organic materialmay be disposed on the color filter 230. The light blocking member 220may have openings arranged in a matrix.

An upper passivation layer 180 q made of a transparent organicinsulating material may be disposed on the color filter 230 and thelight blocking member 220. The upper passivation layer 180 q preventsthe color filter 230 from being exposed and provides a flat surface. Theupper passivation layer 180 q has a plurality of contact holes 185 a andcontact holes 185 b exposing the first drain electrodes 175 a and seconddrain electrodes 175 b.

A plurality of pixel electrodes 191 are disposed on the upperpassivation layer 180 q. The pixel electrodes 191 may be formed with atransparent conductive material such as Indium Tin Oxide (ITO) andIndium Zinc Oxide (IZO), or with a reflective material such as aluminum,silver, chromium, and alloys thereof.

The pixel electrode 191 includes a first sub-pixel electrode 191 a and asecond sub-pixel electrode 191 b separated from each other by a gap 91.The first sub-pixel electrode 191 a and the second sub-pixel electrode191 b may include electrodes like the basic electrode 199 shown in FIG.5 or variants thereof.

The basic electrode 199 will now be described in detail with referenceto FIG. 4 and FIG. 5.

As shown in FIG. 5, the basic electrode 199 is quadrangular-shaped, andhas a cross-shaped stem portion with a transverse stem 193 and alongitudinal stem 192, each extending perpendicular to the other.Furthermore, the basic electrode 199 is partitioned into first to fourthsub-regions (first sub-region Da, second sub-region Db, third sub-regionDc, and fourth sub-region Dd, collectively, “sub-regions D”) by way ofthe transverse stem 193 and the longitudinal stem 192. Also, the firstsub-region Da has a plurality of first mini-branches 194 a, the secondsub-region Db has a plurality of second mini-branches 194 b, the thirdsub-region Dc has a plurality of third mini-branches 194 c, and thefourth sub-region Dd has a plurality of fourth mini-branches 194 d.Collectively, the plurality of first mini-branches 194 a, the pluralityof second mini-branches 194 b, the plurality of third mini-branches 194c, and the plurality of fourth mini-branches 194 d are referred to as“mini branches 194.”

The plurality of first mini-branches 194 a extends diagonally toward thetop left of the page from the transverse stem 193 or the longitudinalstem 192. The plurality of second mini-branches 194 b extends diagonallytoward the top right of the page from the transverse stem 193 or thelongitudinal stem 192. The plurality of third mini-branches 194 cextends diagonally toward the bottom left of the page from thetransverse stem 193 or the longitudinal stem 192. The plurality offourth mini-branches 194 d extends diagonally toward the bottom right ofthe page from the transverse stem 193 or the longitudinal stem 192.

The mini-branches 194 are angled to the longitudinal stem 192 or thetransverse stem 193 by about 45 or 135 degrees. Furthermore, themini-branches 194 of two neighboring sub-regions (for example,sub-region Da and sub-region Db) may extend perpendicular to each other.

The width of the mini-branches 194 may be in the range of 2.0 μm to 5.0μm, and the interval between the neighboring mini-branches 194 of one ofsub-regions D may be in the range of 2.5 μm to 5.0 μm.

Although not shown in the drawing, the widths of the mini-branches 194closer to the transverse stem 193 or the longitudinal stem 192 may begreater than the widths of the mini-branches further away from thetransverse stem 193 or the longitudinal stem 192.

Referring to FIG. 2, FIG. 3, FIG. 4, and FIG. 5 again, the firstsub-pixel electrode 191 a and the second sub-pixel electrode 191 b eachinclude one basic electrode 199. However, the area of the secondsub-pixel electrode 191 b of the pixel electrode 191 may be larger thanthe area of the first sub-pixel electrode 191 a. In this case, the areaof the second sub-pixel electrode 191 b is larger than the area of thefirst sub-pixel electrode 191 a by 1.0 to 2.2 times.

The second sub-pixel electrode 191 b includes a pair of branches 195extending parallel to the data lines 171 a and the data lines 171 b. Thebranches 195 are disposed between the first sub-pixel electrode 191 aand the data lines 171 a and data lines 171 b, and are connected to aportion of the first sub-pixel electrode 191 a near the bottom of thepage. The first sub-pixel electrode 191 a and the second sub-pixelelectrode 191 b are physico-electrically connected to the first drainelectrode 175 a and the second drain electrode 175 b through the contacthole 185 a and the contact hole 185 b, respectively, so as to receivedata voltages from the first drain electrode 175 a and the second drainelectrode 175 b.

The common electrode panel 200 will now be described in detail.

Referring to the common electrode panel 200, a common electrode 270 isdisposed on the entire surface of a transparent insulation substrate210.

Spacers 363 space the common electrode panel 200 and the thin filmtransistor array panel 100 apart from each other.

Alignment layer 11 and alignment layer 21, which may be verticalalignment layers, are respectively coated on the inner surface of thethin film transistor array panel 100 and the common electrode panel 200.The alignment layer 11 and the alignment layer 21 may include at leastone of materials generally used as a liquid crystal alignment layer,such as, for example, polyamic acid, a polyimide or a polysiloxane. Thealignment layer 11 and the alignment layer 21 include the firstalignment polymer 13 a or the first alignment polymer 23 a formed byirradiating the first alignment aids 13 or the first alignment aids 23,respectively.

Polarizers (not shown) may be provided on the outer surfaces of the thinfilm transistor array panel 100 and the common electrode panel 200.

A liquid crystal layer 3 is formed between the thin film transistorarray panel 100 and the common electrode panel 200. The liquid crystallayer 3 includes a plurality of liquid crystal molecules 310, and asecond alignment polymer 50 a formed by irradiating light to a secondalignment aid 50.

The liquid crystal molecules 310 have negative dielectric anisotropy,and may be oriented such that the major axes thereof are almostperpendicular to the surfaces of the thin film transistor array panel100 and the common electrode panel 200 when no electric field isapplied.

If voltages are applied to the pixel electrode 191 and the commonelectrode 270, the liquid crystal molecules 310 respond to the electricfield generated between the pixel electrode 191 and the common electrode270 such that the long axes thereof tend to become perpendicular to theelectric field direction. The degree of polarization of the light thatis incident to the liquid crystal layer 3 is changed according to theinclination degree of the liquid crystal molecules 310, and this changeof polarization appears as a change of transmittance by the polarizer,thereby displaying images of the liquid crystal display.

The inclination direction of the liquid crystal molecules 310 isdetermined by the mini-branches 194 of the pixel electrodes 191. Theliquid crystal molecules 310 are inclined in the direction parallel tothe length direction of the mini-branches 194. In an exemplaryembodiment of the present invention, the mini-branches 194 of one pixelPX are extended in four directions such that the inclined directions ofthe liquid crystal molecules 31 are all four directions. Thereby, fourdomains having different alignment directions of the liquid crystalmolecules 310 are formed in the liquid crystal layer 3. Therefore, theviewing angle of the liquid crystal display may be widened by varyingthe inclined directions of the liquid crystal molecules.

The first alignment polymer 13 a, the first alignment polymer 23 a, andthe second alignment polymer 50 a formed by the polymerization of thefirst alignment aids 13, the first alignment aids 23, and the secondalignment aids 50, respectively, control a pre-tilt as an initialalignment direction of the liquid crystal molecules 310. The firstalignment aids 13, the first alignment aids 23, and the second alignmentaids 50 may be a reactive mesogen.

The first alignment aids 13, the first alignment aids 23, and the secondalignment aids 50 may be represented by Equation 1.

Here, m and n are independently 0 or 1.

“A” represents a reactive mesogen. The mesogen includes a structure inwhich two or more aromatic or aliphatic cyclic compounds are connectedto each other at the center thereof.

“A” of Equation 1 may be any of the compounds represented by Formulae 1to 7.

An outer hydrogen atom of the ring in the compound of the ring structurecorresponding to “A” may be substituted with one of F, Cl, OCF3, OCH3,and an alkyl group of 1 to 6 carbon atoms. The first alignment aids 13,the first alignment aids 23, and the second alignment aids 50 may be anyof the compounds represented by Formulae A to E.

In Equation 1, Z1 and Z2 each may independently be any of the compoundsrepresented by Formulae 8 to 12, and when m or n is 0, A and B1, or Aand B2 may be single bonds.

B1 and B2 as the terminal group of the first alignment aids 13 and thefirst alignment aids 23 or the second alignment aids 50 may correspondto a photo-polymerizable group.

In Equation 1, B1 and B2 may independently be any of the compoundsrepresented by Formulae 13 and 14. However, B1 and B2 corresponding tothe photo-polymerizable group are a functional group that is able to bepolymerized by light, and are not limited to Formulae 13 and 14.

Z1 and Z2 may independently be a chain alkyl group of 3 to 12 carbonatoms disposed between the mesogen and the photo-polymerizable group.The chain alkyl group is disposed between the mesogen and thephoto-polymerizable group thereby controlling a chain length such thatit increases the polymerization degree when the first alignment aids 13and the first alignment aids 23 or the second alignment aids 50 receivelight.

The first alignment aids 13 and the first alignment aids 23 are in therange of 0.1 wt % to 20 wt % of the entire weight including thealignment layer 11, the alignment layer 21, the first alignment aids 13and the first alignment aids 23. When the first alignment aids 13 andthe first alignment aids 23 are less than 0.1 wt %, it is difficult tocontrol the pre-tilt direction of the liquid crystal molecules 310, andwhen the first alignment aids 13 and the first alignment aids 23 aremore than 20 wt %, the remaining alignment aids that are not polymerizedafter polymerizing may contain impurities.

A polymerization initiator may be included along with the firstalignment aids 13 and the first alignment aids 23. The polymerizationinitiator may be 1 wt %. When including the polymerization initiator,the polymerization may occur quickly. However, the unreactedpolymerization initiator is a remaining material that may be an impuritywhen it is present in an excessively large amount.

The second alignment aids 50 are in the range of 0.01 wt % to 1.0 wt %of the entire weight including the liquid crystal molecules 310 and thesecond alignment aids 50. When the second alignment aids 50 are lessthan 0.01 wt %, it is difficult to control the pre-tilt of the liquidcrystal molecules 310, and when the second alignment aids 50 are morethan 1.0 wt %, the content of the liquid crystal molecules 310 isdecreased such that the display characteristic may be deteriorated.

The first alignment aids 13, the first alignment aids 23, and the secondalignment aids 50 may be polymerized.

This will be described with reference to FIG. 6A and FIG. 6B as well asFIG. 2, FIG. 3, FIG. 4, and FIG. 5.

FIG. 6A and FIG. 6B are schematic diagrams showing a method for forminga pre-tilt of liquid crystal molecules through alignment aids accordingto an exemplary embodiment of the present invention.

Firstly, a thin film transistor array panel 100 and a common electrodepanel 200 are respectively manufactured.

The thin film transistor array panel 100 is manufactured through thefollowing method.

A plurality of thin films are deposited on an insulation substrate 110,and are patterned to sequentially form a gate line 121 including a firstgate electrode 124 a and a second gate electrode 124 b, a gateinsulating layer 140, a semiconductor 154 a and a semiconductor 154 b,data lines 171 a and data lines 171 b (respectively including a sourceelectrode 173 a and a source electrode 173 b), a drain electrode 175 aand a drain electrode 175 b, and a lower passivation layer 180 p.

Next, a color filter 230 is disposed on the lower passivation layer 180p, and a light blocking member 220 preventing light leakage is disposedon the color filter 230. An upper passivation layer 180 q is disposed onthe light blocking member 220 and the color filter 230.

A conductive layer such as ITO or IZO is deposited on the upperpassivation layer 180 q, and is patterned to form a pixel electrode 191including a longitudinal stem 192, a transverse stem 193, and aplurality of mini-branches 194 extended therefrom.

Next, an alignment layer 11 including the first alignment aids 13 iscoated on the pixel electrode 191.

The common electrode panel 200 is manufactured through the followingmethod.

A common electrode 270 is disposed on a transparent insulation substrate210. An alignment layer 21 including the first alignment aids 23 iscoated on the common electrode 270.

Next, the thin film transistor array panel 100 and the common electrodepanel 200 that are manufactured through the above-described method areassembled, and a liquid crystal layer 3 is formed by injecting a mixtureof liquid crystal molecules 310 and the above-described second alignmentaids 50 therebetween. Alternatively, the liquid crystal layer 3 may beformed by a method in which the mixture of the liquid crystal molecules310 and the second alignment aids 50 is dripped on the thin filmtransistor array panel 100 or the common electrode panel 200.

Next, referring to FIG. 6A and FIG. 5, voltages are applied to the pixelelectrode 191 and the common electrode 270. The first alignment aids 13and the first alignment aids 23 included in the alignment layer 11 andthe alignment layer 21 are extended from the inner part of the alignmentlayer 11 and the alignment layer 21 thereby forming a pre-tilt. Theliquid crystal molecules 310 and the second alignment aids 50 areinclined in a direction parallel to the length direction of the minutebranches 194 a-194 d of the pixel electrode 191 by the application ofthe voltages.

First light 1 is irradiated in a state in which the voltages are appliedbetween the pixel electrode 191 and common electrode 270. The firstlight 1 has a wavelength, such as ultraviolet rays, that can polymerizethe first alignment aids 13, the first alignment aids 23, and the secondalignment aids 50.

Referring to FIG. 6B, the first alignment polymers 13 a and the firstalignment polymers 23 a extended from the alignment layer 11 and thealignment layer 21 are formed by polymerizing the first alignment aids13 and the first alignment aids 23 included in the alignment layer 11and the alignment layer 21 after the light irradiation, and theneighboring second alignment aids 50 are light-polymerized therebyforming the second alignment polymers 50 a. The first alignment polymers13 a, the first alignment polymers 23 a, and the second alignmentpolymers 50 a are arranged according to the alignment of the liquidcrystal molecules 310, and the arrangement is maintained after theapplied voltage is removed thereby controlling the pre-tilt of theliquid crystal molecules 310.

FIG. 7 is a layout view of a liquid crystal display according to anotherexemplary embodiment of the present invention, and FIG. 8 is across-sectional view taken along the line VIII-VIII′ of FIG. 7.

Different elements from the previous exemplary embodiment will bedescribed in the current exemplary embodiment of the present invention.

Referring to FIG. 7 and FIG. 8, a liquid crystal display according to anexemplary embodiment of the present invention includes a thin filmtransistor array panel 100 and a common electrode panel 200 facing eachother, and a liquid crystal layer 3 interposed between the thin filmtransistor array panel 100 and the common electrode panel 200.

A plurality of thin films are deposited on an insulation substrate 110and are patterned to sequentially form a gate line 121 including a firstgate electrode 124 a and a second gate electrode 124 b, a gateinsulating layer 140, a semiconductor 154 a and a semiconductor 154 b,data lines 171 a and data lines 171 b (respectively including a sourceelectrode 173 a and a source electrode 173 b), a drain electrode 175 aand a drain electrode 175 b, and a lower passivation layer 180 p.

A partition is disposed on the lower passivation layer 180 p. Thepartition is formed according to the gate line 121, the data line 171 aand the data line 171 b, and is also disposed on the thin filmtransistor. A region enclosed by the partition substantially forms arectangle as a filling region where a color filter 230 is disposed.

The partition includes a first partition 361 a disposed on the thin filmtransistor, and a second partition 361 b disposed on the data lines 171a and the data lines 171 b. Specifically, the first partition 361 a hasopenings “G” through which the first drain electrodes 175 a and thesecond drain electrodes 175 b are exposed. The second partition 361 b isdisposed between neighboring data line 171 a and data line 171 b suchthat it partially overlaps the data line 171 a and the data line 171 b.

An inkjet material for color filters 230 fills the region surrounded bythe partition 361 a and the partition 361 b. The color filters 230 maybe formed through inkjet printing. An upper passivation layer 180 q isdisposed on the color filters 230. The upper passivation layer 180 q isalso disposed on the partition 361 a and the partition 361 b so as toflatten the underlying layer.

The upper passivation layer 180 q may be formed of a photosensitiveorganic material. In addition to the openings G, a contact hole 185 aand a contact hole 185 b are formed at the upper passivation layer 180 qso as to expose the first drain electrode 175 a and the second drainelectrode 175 b.

A plurality of pixel electrodes 191 are disposed on the upperpassivation layer 180 q. The pixel electrodes 191 may be formed with atransparent conductive material such as ITO and IZO, or with areflective material such as aluminum, silver, chromium, and alloysthereof.

Referring to the common electrode panel 200, a common electrode 270 isdisposed on a transparent insulation substrate 210.

A spacer 363 for maintaining an interval between the common electrodepanel 200 and the thin film transistor array panel 100 is disposed onthe gate line 121 or the thin film transistor. The spacer 363 disposedon the thin film transistor overlaps the first source electrode 173 a orsecond source electrode 173 b and the first drain electrode 175 a orsecond drain electrode 175 b, and may fill the opening “G” of the firstpartition 361 a and the contact hole 185 b of the upper passivationlayer 180 q on the pixel electrode 191.

Alignment layer 11 and alignment layer 21, which may be verticalalignment layers, are respectively coated on the inner surface of thethin film transistor array panel 100 and the common electrode panel 200.

Polarizers (not shown) may be provided on the outer surfaces of the thinfilm transistor array panel 100 and the common electrode panel 200.

A liquid crystal layer 3 is formed between the thin film transistorarray panel 100 and the common electrode panel 200. The liquid crystallayer 3 includes the second alignment polymer 50 a formed by irradiatinglight to a plurality of liquid crystal molecules 310 and the secondalignment aids 50.

The liquid crystal molecules 310 have negative dielectric anisotropy,and may be oriented such that the major axes thereof are almostperpendicular to the surfaces of the thin film transistor array panel100 and the common electrode panel 200 when no electric field isapplied.

The descriptions of the alignment layer 11 and the alignment layer 21,the first alignment aids 13 and the first alignment aids 23, the secondalignment aids 50, the first alignment polymers 13 a and the secondalignment polymers 23 a, and the second alignment polymers 50 a in theabove-described exemplary embodiment of the present invention may alsobe applied here.

Next, for when the alignment layers and the liquid crystal layer 3include the alignment aids, a voltage holding ratio and an afterimageimprovement effect will be described.

FIG. 9 is a graph showing a voltage holding ratio according to existenceof alignment aids in a liquid crystal layer.

Referring to Table 1, the voltage holding ratio is decreased about 1.0%to 1.1% by the exposure of 50 J/_(cm) ² for the case in which the liquidcrystal layer 3 does not include a reactivity mesogen (RM)(corresponding to Comparative Example 1 and Comparative Example 2, inFIG. 9). However, when the liquid crystal layer 3 includes thereactivity mesogen (RM), the voltage holding ratio by the same exposuredecreases about 0.1% to 0.2%. FIG. 9 shows this effect.

TABLE 1 Content of Voltage Voltage Difference of RM in an Existence ofRM holding holding voltage alignment in liquid crystal ratio (beforeratio (after holding layer (content) exposure) exposure) ratiosComparative 1% No 99.99% 95.96% −1.02667% Example 1 Exemplary 1% Yes(0.2%) 97.66% 97.55% −0.11667% embodiment 1 Comparative 2% No 98.25%97.09% −1.16667% Example 2 Exemplary 2% Yes (0.2%) 98.69% 98.43%  −0.26% embodiment 2

FIG. 10A, FIG. 10B, FIG. 10C, and FIG. 10D are graphs showing variationof a voltage holding ratio according to an irradiation amount ofultraviolet (UV) rays.

FIG. 10A shows a voltage holding ratio according to exposure energy inthe case of UV exposure in a condition of 60 Hz and 22 degrees Celsius.FIG. 10B shows a voltage holding ratio according to exposure energy inthe case of UV exposure in a condition of 60 Hz and 60 degrees Celsius.FIG. 10C shows a voltage holding ratio according to exposure energy inthe case of UV exposure in a condition of 5 Hz and 22 degrees Celsius.FIG. 10D shows a voltage holding ratio according to exposure energy inthe case of UV exposure in a condition of 5 Hz and 60 degrees Celsius.

In the case of Comparative Example 1 and Comparative Example 2 in whichthe liquid crystal layer does not include the alignment aids, the liquidcrystal layer is damaged by UV such that the voltage holding ratio islargely reduced. As the exposure energy is increased, the voltageholding ratio is greatly reduced.

However, in the case of Exemplary Embodiment 1 and Exemplary Embodiment2 in which the liquid crystal layer includes the alignment aids,although the exposure energy is large, the voltage holding ratio isminimally reduced.

FIG. 11 is a graph showing an afterimage according to existence ofalignment aids of a liquid crystal layer.

Referring to Table 2, in the case of Comparative Example 1 andComparative Example 2 in which the liquid crystal layer does not includethe alignment aids (RM), an elimination voltage of the surfaceafterimage is in the range of 3.8V to 4.0V. However, in the case ofExemplary Embodiment 1 and Exemplary Embodiment 2 in which the liquidcrystal layer includes the alignment aids (RM), the elimination voltageof the surface afterimage is about 3.2V.

TABLE 2 Content of RM in an alignment layer 1 wt % 2 wt % Liquid crystalExemplary Exemplary Comparative 1 Embodiment 1 Comparative 2 Embodiment2 Exposure amount 30 40 50 60 70 30 40 50 60 70 30 40 50 60 70 30 40 5060 70 (J/cm²) Elimination voltage 4.1 3.9 4 3.8 3.9 3.2 3.3 3.25 3.153.2 X 3.8 3.65 3.95 3.8 3.3 3.2 3.1 3.2 3.2 of the surface afterimage(V)

Thus, in the case that the alignment layer and the liquid crystal layerboth include the alignment aids (RM), the elimination voltage of thesurface afterimage is improved about 0.7V compared with the case of onlythe alignment layer including the alignment aids (RM). This resultappears in FIG. 11.

It will be apparent to those skilled in the art that variousmodifications and variation can be made in the present invention withoutdeparting from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A liquid crystal display comprising: a first substrate; a secondsubstrate facing the first substrate; a field generating electrodedisposed on at least one of the first substrate and the secondsubstrate; an alignment layer disposed on the field generatingelectrode, the alignment layer comprising an alignment agent and a firstalignment polymer; and a liquid crystal layer interposed between thefirst substrate and the second substrate, the liquid crystal layercomprising liquid crystal molecules and a second alignment polymer,wherein the first alignment polymer is formed by light-irradiating thealignment agent and first alignment aids, and the second alignmentpolymer is formed by light-irradiating the liquid crystal molecules andsecond alignment aids, and wherein the first alignment aids and thesecond alignment aids comprise a mesogen and a photo-polymerizable groupcoupled to the mesogen.
 2. The liquid crystal display of claim 1,wherein the field generating electrode has a plurality of mini branches,and the width of the mini branches is in the range of 2 to 5micrometers.
 3. The liquid crystal display of claim 1, wherein the firstsubstrate is a thin film transistor substrate, the second substrate is acommon electrode substrate, and the thin film transistor substratecomprises at least one of a color filter and a black matrix.
 4. Theliquid crystal display of claim 1, wherein the first alignment aids andthe second alignment aids are represented by Equation 1:

where m and n are independently 0 or
 1. 5. The liquid crystal display ofclaim 4, wherein, in Equation 1, A comprises a compound represented byone of Formulae 1 to 7:


6. The liquid crystal display of claim 5, wherein, in Equation 1, Z1 andZ2 each independently comprise a compound represented by one of Formulae8 to 12:

if morn is 0, A and B1, or A and B2, are single bonds.
 7. The liquidcrystal display of claim 6, wherein, in Equation 1, B1 and B2 eachindependently comprise a compound represented by one of Formulae 13 and14:


8. The liquid crystal display of claim 5, wherein, in Formulae 1 to 7,an outer hydrogen atom is substituted with one of F, Cl, OCF3, OCH3, andan alkyl group of 1 to 6 carbon atoms.
 9. The liquid crystal display ofclaim 1, wherein the alignment agent is one of polyamic acid, apolyimide, and a polysiloxane.
 10. The liquid crystal display of claim9, wherein the first alignment aids are included at 0.1 wt % to 20 wt %with respect to the total content of the alignment layer.
 11. The liquidcrystal display of claim 1, wherein the second alignment aids areincluded at 0.01 wt % to 1.0 wt % with respect to the total content ofthe liquid crystal layer.
 12. A method for manufacturing a liquidcrystal display, comprising: forming a field generating electrode on atleast one of a first substrate and a second substrate, the secondsubstrate facing the first substrate; forming an alignment layer on thefield generating electrode, the alignment layer comprising an alignmentagent and first alignment aids; assembling the first substrate and thesecond substrate; forming a liquid crystal layer between the firstsubstrate and the second substrate, the liquid crystal layer comprisingliquid crystal molecules and second alignment aids; applying a voltagebetween the first substrate and the second substrate; and forming afirst alignment polymer and a second alignment polymer bylight-irradiating the alignment layer and the liquid crystal layer, in astate in which the voltage is applied between the first substrate andthe second substrate.
 13. The method of claim 12, wherein the fieldgenerating electrode has a plurality of mini branches, and the width ofthe mini branches is in the range of 2 to 5 micrometers.
 14. The methodof claim 12, wherein the first alignment aids and the second alignmentaids are represented by Equation 1:

where, m and n are independently 0 or
 1. 15. The method of claim 14,wherein, in Equation 1, A comprises a compound represented by one ofFormulae 1 to 7:


16. The method of claim 15, wherein, in Equation 1, Z1 and Z2 eachindependently comprise a compound represented by one of Formulae 8 to12:

if morn is 0, A and B1, or A and B2, are single bonds.
 17. The method ofclaim 16, wherein, in Equation 1, B1 and B2 each independently comprisea compound represented by one of Formulae 13 and 14:


18. The method of claim 15, wherein, in Formulae 1 to 7, an outerhydrogen atom is substituted with one of F, Cl, OCF3, OCH3, and an alkylgroup of 1 to 6 carbon atoms.
 19. The method of claim 12, wherein thealignment agent is one of polyamic acid, a polyimide, and apolysiloxane.
 20. The method of claim 12, wherein the forming of thefirst alignment polymer and the second alignment polymer furthercomprises irradiating the light in a state in which the voltage is notapplied after the light-irradiating.
 21. The method of claim 12, whereinthe first substrate is a thin film transistor substrate, the secondsubstrate is a common electrode substrate, and the thin film transistorsubstrate comprises at least one of a color filter and a black matrix.22. The method of claim 21, wherein the first substrate comprises acolumn spacer to form a cell gap within the liquid crystal molecules.23. The method of claim 22, wherein the column spacer is disposedbetween neighboring pixel areas.
 24. The method of claim 23, wherein thecolumn spacer comprises a transparent material or an opaque material.25. The method of claim 24, wherein the black matrix and the columnspacer are simultaneously formed.